In an electric oven, heating or incandescent wires are used in order to be able to heat the interior of the oven. The heating wires are made from a metal which is able to conduct electricity well and can be heated to the desired high temperatures without the material deforming. The heating wires have to be kept a certain distance apart so that the temperature of the oven can be kept as even as possible throughout. To this end, the heating wires are kept apart by means of spacer pieces or spacer strips. However, the hotter the heating wires become, the softer the material from which the heating wires are made will become. In a horizontal oven, where the heating wires are arranged in a helical or meandering fashion, i.e., run more or less to and fro, the heating wires will become softer as the temperature increases and, beyond a certain temperature, the risk that the wires will sag under their own weight and by the effect of gravity will increase. As a result, not only will the oven not be heated as evenly throughout as desired, but also the sagging heating wires can come into contact with materials which are in the oven. The heating wires in a horizontal oven will therefore have to be supported, especially if the wires are located at the top of the oven, so that the wires no longer sag when, due to the heating of the wires, the material from which they are made becomes so soft that they start to sag as a result of their own weight. However, care should also be taken to ensure that the heating wires are not clamped in, as the wires expand on heating and need a sufficient degree of freedom of movement as there is otherwise a great risk of the wires snapping. This is of particular importance with horizontal ovens in which semiconductor materials are treated, as the treatment in these ovens is effected at high temperatures, which may cause the heating wires which have become too soft to sag.